I would agree with SD if you are only talking 300 yards.
I would want the BP reticle too. As far as the 3-12 not being suited to cartridges in the 308 class and above I would disagree. I have or have had 3-12's on a 260 Rem, 6.5x57Rimmed, 6mm-284, two 6.5-284's, 284 Winchester, and a 7.82 Patriot (tad bigger than a 300WSM). I have not had a problem with any of these scopes and have put quite a few rounds through some of these specialty handguns.